Skip to content

Posts from the ‘Space’ Category

14
Jan

Vandenberg Shuttle Launch Complex

Not many people know that once upon a time, NASA built a Space Shuttle Launch Complex at Vandenberg Air Force Base in California, 1985. It was later dismantled, and no Shuttle was ever launched. Oh, how I wish they had kept it! I would’ve seen so many more launches, not having to travel across the country for each one.

Spaceflight Now has posted a series of articles with lots of photos from the era. Really great stuff.

Looks fake, doesn’t it? It’s not. It was built.

Each of these articles has a whole slew of images:

19
Sep

Balloon Controller

I’m probably just procrastinating a bit before getting into writing firmware for this thing, but I though I’d post a picture of the Balloon Controller with nearly everything populated. I’m still waiting for the barometric pressure sensor and GPS connector to arrive, but everything else is installed.

Balloon Controller

I’ve verified that everything powers up, but beyond that, I have no idea if anything works. I was able to flash the MC with a blinky LED program, though, so that’s a good start.

UPDATE (15:38): Got the DBGU serial port work. Note that this board has two USB ports. One for the MC proper, and one for an FTDI chip attached to the SAM7X’s DBGU port. This was easier than writing a Mac OS X virtual serial port driver against the MC’s USB port.

DBGU Port Working

UPDATE (18:27): Got the battery voltage being measured, and also got the radio link working!

It’s a little cumbersome to flash the MC when you have an external power source, because it needs to power cycle to re-enumerate the USB and set up for download. So I pulled the fuse that USB bus power goes through, which means that I only have to disconnect the main power supply to power cycle it, rather than disconnect that and unplug the USB cable.

18
Sep

18 km Range Test a Success

Darren and I tried an 18 km range test today with the n920. Amazingly, we had success with just the rubber ducky antennas, and down to 250 mW transmit power on both ends! He was up near this winery, and I was on the fifth floor of Yahoo! building D.

At first we tried the new Yagi, but it didn’t seem to work (at all). We were astonished to get a link with just the whip antennas. They didn’t even have a proper ground plane, just being stuck out the side of the plastic boxes I had put the gear in (and pointing upward).

Using the ATS123? command to query the receive signal strength, Darren had -88 dBm, I had -105 dBm (measurements varied, but I think that was at 250 mW). I tried sending a file to myself via loopback, < 1 KB in length, which failed the first time and succeeded the second. A 131 KB file failed, and I didn’t try it a second time. I could see it dropped stuff from within the file. We’ll have to investigate exactly what went on. Are the radios full duplex? How big are their buffers? It seemed to send the entire file before receiving anything, but that could’ve been an artifact of PortTermX.

Interestingly, the Yagi didn’t seem to offer much. It was also nearly impossible to hold while operating the computer. Next time, we need to put it on a stand of some kind.

Hopefully this weekend we’ll try a much longer range test, from the winery to Coyote Hills.

« Older Entries